The present invention relates to a device for matching of a picture tube, said picture tube having a base connector comprising a plurality of electrical terminals, one of which is connected to means for preheating of a cathode in the picture tube, said device comprising a product carrier arranged to carry said picture tube along a matching line to a matching position, said carrier being connected to a voltage source, and a matching means, located in the matching position for performing the matching of the tube.
The invention also relates to a connecting socket, intended to be mounted onto and electrically connected to a picture tube base connector.
In a matching process for picture tubes (CRT), the tubes are preheated for a period of 30 minutes, followed by the adjustment of the deflection unit. During the preheating, a filament in the tube is connected to a heater voltage, and during the matching, the tube connected to several control voltages.
When picture tubes are matched in a production line, product carriers are normally used for transporting the tubes, and each carrier is connected to a heating voltage source via the transportation line. The tube is electrically connected to a connecting device on the carrier by several wires, one of which secures pre heating of the tube during transportation in the line. When the carrier stops in a working position, a measuring instrument is automatically connected to the connecting device. A device of this kind, where the measuring instrument is connected from the side, is disclosed in GB 2326973. Another way to accomplish the connection is to provide the connecting device on under side of the carrier, and the terminal unit of the measuring instrument is connected from underneath.
A problem with this type of connection arrangement is the need for relatively long (several decimeters) wires between the picture tube and the connecting device on the carrier. The long wiring makes it difficult to achieve a high quality signal when high frequencies are used for the matching process, and for frequencies above 60 kHz the problems with deterioration of picture quality are significant.
Another drawback is the fact that the connection of the control wiring to the tube base has to be provided on every product carrier, normally more than one hundred in a manufacturing plant.
The connector in the picture tube base comprises several parallel connection pins, and known connectors are arranged to connect to all these pins at the same time. Therefore, in order to connect the terminal unit of the measuring instrument directly to the picture tube in the matching position, the connection for the preheating voltage would have to be removed to allow for connection of the terminal unit.
An object of the present invention is thus to overcome these problems, and to provide a device for matching a CRT without the need for excessively long wires.
A second object is to provide an improved device for connecting a heating voltage to a picture tube during matching.
These objects are accomplished by a connecting socket, adapted to be mounted onto and electrically connected to said picture tube base connector, which connecting socket comprises a first terminal for connection of said filament to said voltage supply via the carrier, and a plurality of second terminals for separate, simultaneous connection of said matching means directly to said socket.
The connecting socket, intermediate between the base connector and the matching means, is adapted to connect the heating voltage to the filament of the tube, while still permitting the direct connection of the control voltages. The term xe2x80x9cdirectxe2x80x9d is here understood to mean that no intermediate wires are needed. Thus it is possible to connect the matching means directly to the tube, eliminating the need for long wires.
The intermediate socket thus makes it possible to keep the preheating voltage connected to the filament as long as the tube is placed on the pallet, while the control voltage connections are made directly to the tube in the matching position.
According to prior art, as was described above, the connection of the control voltages were made in two steps: First, a multi-wire connection was provided between the base connector and the carrier, thereby allowing for connection of the heating voltage. Then, a connecting device on the carrier was connected directly to the matching means.
As the intermediate socket according to the invention only needs one connection (the heating voltage), the connection between the picture tube and the product carrier is simplified. Instead of comprising wiring to all the control voltages, there is only one wire, and this wire only connects a low voltage (the heating voltage is typically under 10 V). This means that maintenance of the product carriers (around 100 in a normal manufacturing plant) is facilitated. A complete tube base connection is only required in the match positions, and not on every product carrier all the time.
The plurality of second terminals can consist of parallel connecting elements, similar to the ones present in a conventional picture tube base connector. Preferably the plurality of second terminals are connectable to a connector initially intended for connection with a picture tube base connector. This makes it possible to use the connecting socket in existing installations with very little adjustment.
A second aspect of the invention relates to a device for matching of a picture tube, comprising such a connecting socket. Preferably, the matching means is directly engageable/disengageable with said connecting socket without disconnecting the heating voltage. This results in a simple procedure for connecting the matching means.
In a preferred embodiment, the matching means comprises a connector portion, which is transversely movable to engage with said connecting socket mounted on a picture tube. This enables easy operation at the matching position.
The connecting socket can be connected to the carrier with the means of a wire, supplying the connecting socket with voltage for the preheating means.